Velocity Verlet NpT is wrong for rotating particles

[jngrad]

Velocity Verlet NpT doesn't apply friction and noise on angular velocities. When a rotating particle is subjected to an external torque, its angular momentum keeps increasing until it becomes NaN.

MWE:

import espressomd
system = espressomd.System(box_l=[1., 1., 1.], time_step=0.01)
system.cell_system.skin = 0.
p = system.part.add(pos=[0, 0, 0], v=[1, 2, 3], omega_lab=[1, 2, 3], rotation=3 * [True])
system.thermostat.set_npt(kT=0., gamma0=2., gammav=1e-6, seed=42)
system.integrator.set_isotropic_npt(ext_pressure=0.01, piston=1e6)
system.integrator.run(1)
print(f"{p.v=}")
print(f"{p.omega_lab=}")

Output on the python branch and in releases 4.2.1 and 4.1.4:

p.v=array([0.9801, 1.9602, 2.9403])
p.omega_lab=array([1., 2., 3.])

Output on the python branch and in releases 4.2.1 and 4.1.4 with kT=1:

p.v=array([0.77535126, 1.85724279, 3.01009923])
p.omega_lab=array([1., 2., 3.])